1. Field of the Invention
The present invention relates to a facsimile system for connection to a telephone circuit.
2. Description of the Related Art
Conventional facsimile systems are generally classified into the following groups: (1) Facsimile systems which prohibit the operator from taking any other actions on the facsimile systems while they are receiving messages; (2) Full-duplex facsimile system in which a transmitter and a receiver are completely separated from each other for simultanous message transmission and reception; and (3) Facsimile systems in which a received signal is temporarily stored in a memory having a large storage capacity such as a hard disk, and the stored message is read out when desired to produce a hard copy thereof (see, for example, Japanese Laid-Open Patent Publication No. 58-139562).
The facsimile systems in group (1) have a problem in that when the facsimile system is receiving a long message, an operator who wishes to send a message through the facsimile system immediately after the reception is finished must attend the system until the reception is over since the operator does not know when the reception will be completed. Although the facsimile systems in class (2) are free from the foregoing drawback, the cost of the required equipment is high because the system requires two telephone circuits for reception and transmission, and also requires a transmitter and a receiver which are completely independent of each other. The facsimile system in the category (3) allows the operator to send a message directly without going through an internal memory while a received message stored in the internal memory is being printed on a sheet of paper. This facsimile system is also capable of storing a message to be transmitted in the internal memory, if it has an available memory area, even while an incoming message is being stored into the internal memory, so that the outgoing message can automatically be delivered to the circuit immediately after the reception of the incoming message has been completed. Therefore, the operator who wants to transmit the message is not required to attend the facsimile system until the message reception or printing is over. However, the cost of the system is very high because of the mass-storage memory required.